NUMERICAL MODELING OF BARITE MINERALIZATION CAUSED BY MOVEMENT OF A SALINE, HYDROTHERMAL FLUID IN SOUTHEAST MISSOURI

The geologic processes that led to the formation of the Pb-Zn Mississippi Valley-type (MVT) deposits of Southeast Missouri are of interest due to the large scale enrichment of economically significant metals and minerals. Topographically driven-flow generated by uplift of the Arkoma basin caused sufficient movement of saline, hydrothermal fluid for formation of MVT deposits in the St. Francois aquifer. Hydrothermal circulation and mineralization involved in the formation of MVT ore deposits is thought to be limited to the St. François aquifer. The barite district is located up section in the Ozark aquifer within the Potosi and Eminence Dolomites. Modeling of the Ozark aquifer using the Heat and Solute Transport Program (HST3D) will allow a better understanding of the formation process of the economically important barite deposits. A base situation using initial conditions and model parameters established by previous researchers will allow no fluid flow from the St. Francois aquifer to the Ozark aquifer and heat transfer will be limited to conduction-driven transfer only. Simulations using HST3D are expected to show that topographically driven-fluid flow and conduction-driven heat transfer are not sufficient to explain the barite deposits. A variety of heat and transport situations will be performed to evaluate the fluid flow necessary to cause barite mineralization. Transfer of fluid between the St. Francois aquifer and the Ozark aquifer will be simulated by fracturing of the confining unit, thinning of the unit due to the development of a sinkhole, and a combination of scenarios. The results of the numerical solutions will be plots of fluid flow fields and contour maps of temperature and salinities. These maps will be compared to salinities and temperatures determined from fluid inclusion studies of the barite district.